[wellylug] ADSL modem and Linux router/firewall without double NAT

jumbophut jumbophut at gmail.com
Sat Jan 16 20:57:58 NZDT 2010

On 1/7/10, Daniel Reurich wrote:
> Just to document this for those who wish to try it.
> To enable the half Bridge mode on the dynalink rta1320E when using a
> telecom based PPPoA adsl service.

Thanks Daniel.  I have now done this myself using the DSE XH9949 ADSL
router.  I have not done anything fancy so far (just printer-sharing
on the LAN and web browsing from the LAN to outside; no attempt yet to
access anything on the LAN from outside), but as far as I can tell the
half-bridging is working.  The recipe is very similar to yours:

1) connect to the modem using the web interface (in my case I set this
to be, but I think it is by
2) Select "Advanced setup" from the left of the page.
3) Edit the WAN setup (button on the right)
4) Click Next on the first two screens, tick 'PPP IP extension' on the
third and again click Next.
5) Click Next twice more, then save.
6) Reboot the modem (Under 'Management' on the menu at left, but the
power button works also).
7) Configure your Linux-based device (proper router, PC etc) to use
DHCP on the WAN interface, and choose a subnet on the LAN interface
that does not include the modem's subnet (I chose because
the modem was on
8) That's all.  Without further changes I can get the web interface to
both the ADSL modem ( and my router ( from
anywhere on the LAN (I don't explicitly need an alias, as long as I
have set as my default gw; the router finds
just fine).

Happy to provide more details (configs etc.) to others who wish to
try.  I have half-bridged to a stand-alone Linux PC and, once that
worked, to a Linksys WRT54GL running openwrt.

Tony (echo 'spend!,pocket awide' | sed 'y/acdeikospntw!, /l at omcgtjuba.phi/')

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